Lorentz's essay is one of the many written explanations out there of Einstein's Theory of Relativity. So far, the language is mostly accessible to the non-scientist, although some background in geometry might be necessary. I admit it's a bit like reading another language, but I am learning a ton regardless. In COSMOS, Neil DeGrasse Tyson also discussed the outdated idea of an "ether" as the substance of space between the celestial bodies, especially between the Earth and the Sun as a medium through which light travels. When this was disproved and an "ether wind" was not found in relation to the movement of the Earth, this was Einstein's response: a theory positing an explanation for the gravitational movement of the celestial bodies relative to each other.